Ignition magneto



Feb. 9, 1932. B. A. QUINTAVALLE I 1,844,296

IGNITION MAGNETO Filed May 12. 1950 Patented Feb. 9, 1932 1 UNITED, STATES PATENT OFFICE ANTONIO QUINTA'VALLE, F MILAN, ITALY, ASSIGNOR TO FABBRIGA ITALIANA. H MAGNETI MARELLI SOCIETA ANONIMA, OF MILAN, ITALY, A COMPANY OF ITALY IGNITION MAGNETO Application filed May 12, 1930, Serial No. 451,732, and in Italy June 25, 1929.

It is known that in ignition systems of internal combustion engines the ignition point must be advanced with respect to engine piston dead centre and more the number of R. P. M, of the engine is high, more said advance must be large.

The present invention has for its object a device for securing the ignition advance by altering the angle between the magneto rotor and the engine crank shaft, the primary circuit being thus broken always in register with the same position of the magneto rotor with respectto its inductor field, and therefore the spark having always its maximum intensity whatever is the advance imparted to ignition.

;On the annexed-drawingsis illustrated by way of example an embodiment of the present invention, and r j Figure 1 is a fragmentary central longitudinal section of a magneto embodied in accordance with the present invention;

a Figure 2 illustrates a separate part on an enlarged scale and in detail; 7 I

- Figure 3 illustrates another separate part on anenlargedscale and in detail; 1

Figure fl is an end View of Figure 3 Fi ure is a detail ofthe ignition controlling evicewith parts in section.

In the construction illustrated the magneto comprises a rotor 1 mounted on a sleeve 2 which is pivoted in the magneto frame 28 by means of bearings 3, 4; said sleeve 2 has at one end splines providing inward teeth 5 with their faces flat and parallel with axis of rotation.

Inside sleeve 2 a hollow shaft 6 is mounted loose therein, said shaft 6 providing a cone 7 for fastening thereon a ma eto-rotor-actuating pinion or coupling gi ot shown) said shaft 6 has large-pitch helical grooves 9 in its internal open end while at the closed end ofits hollow it has a centering stud 10.

In screw. grooves 9 of hollow shaft 6 is engaged a cooperating screwthread 11 of a bushing 12 which seats in the hollow of shaft 6' and has at its end straight teeth 13 engaging those 5 of sleeve 2, to connect bushing 12 withsleeve 2 in rotation while providing for their respective longitudinal motion.

f A'sprin'g 8 positioned on stud of shaft 6 holds bushing 12 forced towards a shoulder 2 provided by sleeve 2.

A circuit breaking device, of conventional construction and not shown, is located in chamber 27 of magneto frame and it is operated by a cam 26 solid with sleeve-2; it includes a hammer (not shown) which under timed action of cam 26 causes a movable contact to separate from a cooperating stationary contact, the primary circuit being thus interrupted.

In casing 1 1 removably mounted onthe magneto end, straight slots 15 parallel with the axis of sleeve 2 are provided, and in said slots 15 the ends of a cross member 16 are engaged said cross member acting on a central stem 17 whose opposite end abuts against the end of bushing 12. Within casing 14 a box 18 is mounted to rotate, the wall ofothe same having helical slots 19 which also are engaged by cross member 16 and said box 18 may be deviated from outside by means of arm 25 loose on nose 20 of casing 14 and engaged on pins 21 projecting from box 18 through slots 22 of casing 1 1 which slots are shaped as a circle concentric with stem 17; arm is made solid with sleeve 18 by means of split washer 23 engaging notches .of pins 21 and bearing on the face of hub 25 of arm 25; hub 25 has a series of holes 24 intended to receive pins 21 for the purpose of adjusting the normal position of arm 25 in accordance with requirements to be complied with in diflerent types of engines. 7

When magneto shaft 6 is driven in rotation in the direction the magneto is intended to (lefthand in the illustrated construction as seen from cone 7), shaft 6 drives bushing 12 in rotation; bushing 12 in turn drives sleeve 2 and rotor 1 into rotation by means of its teeth 13 in engagement with those 5 of sleeve 2.- 1 Assuming stem 17 to be entirely retracted within its seat and therefore to beinoperative, and shaft 6 be connected under the required angle with engine crank shaft, the magneto is operating with maximum advance because in exemplified case the normal arrangement of parts secures maximum ad- Vance, thatis normal running conditions of the engine.

When advance angle is to be altered, arm is actuated, whose actuating means (not shown) include a device of any known construction holding said arm in any particular position imparted thereto; then deviation of arm 25 is imparted by pins 21 to box 18 whose helical slots 19 move with respect to longitudinal grooves 15 of stationary casing 14; the transverse member 16, being engaged at the same time in slots 19 and grooves 15, is caused tomove parallel to itself and therefore it moves stem 17 against bushing 12 to shift this latter along its axis against action of spring 8 while its teeth 13 slide along those 5 of sleeve 2.

The longitudinal displacement of bushing 12 with respect to hollow shaft 6 which can not revolute faster nor slower it being under preponderatingengine action, causes screwthread 11 of bushing '12 to screw into that 9 of shaft 6 and said bushing 12 to move angularly with respect to said shaft 6; owing to engagement of bushing 12 and sleeve 2 carryingrotor 1 by said teeth 13 and 5 said rotor l'is shifted angularly with respect to engine crank shaft.

Thus the desired value is imparted to ad- Vance while the respective position of rotor 1 with respect to field of inductor 29 and the breaking point of primary circuit are unaffected, because the breaking cam 26 is solid in an unchanged position with respect to magneto rotor 1.

on arm 25 being further shifted in the same direction the advance angle is still reduced, while when arm 25 is moved in opposite direction spring 8 holds bushing 12 forced against stem 17 tofinally carry it again against shoulder 2 of sleeve 2 to restore initial conditions ofr'angular connection intermediate rotor 1 and shaft 6 and maximum angle of advance. Of course the described arrangement is given merely byway of example and is able to be altered within the spirit of appended claims, say in respect of engagement inter mediate driving shaft and rotor and advance control device. Y 7 What I claim as my invention and desire .to secure by United States Letters Patent is:

1. An ignition magneto for combustion engines comprising a stator, a rotor rotatable in said stator and having a splined bore, a hollow shaft having a screwthreaded bore, a. spindle having a' splined portionengaging said rotor splined bore'and a screwthreaded portion engagingsaid shaft screwthreaded bore, and means for shifting longitudinally said spindle.

r 2. An ignition magneto for combustion engines comprising a stator, a rotor rotatable in said stator and having-a bore comprising a plain portion and a'splined portion, a hollow shaft loose in said rotor plain bore and having a screwthreaded bore, an endwise movable spindle having a screwthread'ed'portion engaging said shaft screwthreaded bore and a splined portion engaging said rotor splined bore, and means for shifting longitudinally said spindle.

3. An ignition magneto for combustion engines comprising a stator, a rotor rotatable in said stator and having a bore comprising a plain portion and a splined portion, a hollow shaft loose in said rotor plain bore and having a screwthreaded bore, an endwise movable and hollow spindle having a screwthreaded portion engaging said shaft screwthreaded bore and a splined portion engaging said rotor splined bore, a spring in said hollow shaft andspindle moving them away from each other, a stem endwise movable in said rotor and abutting on said spindle and means for shifting said stem and spindle against said spring.

4. An ignition magneto for combustion engines comprising a stator, a rotor rotatable in said stator, a shaft for driving said rotor, at spindle having a helicoidal groove engaged with either said rotor or shaft and splines engaged with the other of said shaft or rotor, a stem enga ing said spindle for shifting it longitudinally, a stationary member solid with said stator and a second member rotatable with respect to said stationary member, one of said members having sloping engaging means and the other one having engaging means parallel with the axis of said rotatable member, a part engaged with both said first and'second named engaging means and acting on said stem, and means for actuating said rotatable member.

5. An ignition magneto for combustion engines comprising a stator, a rotor rotatable in said stator, a shaft for driving said rotor, a spindle havin a helicoidal groove engaged with either sai rotor or shaft and splines engaged with the other of said shaft or rotor, a stem engaging said spindle for shifting it longitudinally, a stationary member solid with said stator and a second member rotatable with respect to said stationary member, one of said members having sloping engaging means and the other one havi engaging means parallel with the axis of sai rotatable member, a part engaged with both said first andsecond named engaging means and acting on said stem, pins projecting from said rotatable member and an actuating arm engaged with said pins.

6. An ignition magneto for combustion engines comprising a stator, a rotor rotatable in said stator, a shaft for driving said rotor, a spindle havin a helicoidal groove engaged with eithersai rotor or shaft and splines engaged with the other of said shaft or rotor, astem engaging said spindle for shift ing it longitudinally, a stationary member solid with said stator and a second member rotatable with respect to said stationary member, one of said members having sloping engaging means and the other one having engaging means parallel with the axis of said rotatable member, a part engaged with both said first and second named engaging means and acting onsaid stem, pins projecting from said rotatable member and each having a notch, an actuating arm having holes for engagement by said pins and a member engaging said notched pins for clamping said arm thereon.

7. An ignition magneto for combustion engines comprising a stator, a rotor rotatable in said stator and having a bore comprising a plain portion and a splined portion, a hollow shaft loose in said rotor plain bore and having a screw-threaded bore, an endwise movable and hollow spindle having a screw threaded portion engaging said shaft screwthreaded bore and a splined portion engaging said rotor splined bore, a spring in said hollow shaft and spindle moving them away from each other, a stem endwise movable in said rotor and abutting on said spindle, a stationary member solid with said stator and a second member rotatable with respect to said stationary member, one of said members having sloping engaging means and theother one having engaging means parallel with the axis of said rotatable member, a part engaged with both said first and second named engaging means and acting on said stem, pins projecting from said rotatable member and each having a notch, an actuating arm having holes for engagement by said pins and a member engaging said notched pins for clamping said arm thereon.

' 8. An ignition magneto for combustion engines comprising a stator, a rotor rotatable in said stator and having a bore, a hollow shaft extending in a portion of said rotor bore, a spindle extending partly in said rotor bore and partly in said hollow shaft, co-operating teeth in said rotor bore and spindle and in said hollow shaft and spindle said teeth providing a spiral engagement between saidi rotor and shaft, and means for shifting longitudinally said spindle.

9. An ignition magneto for combustion engines comprising a stator, a rotor rotatable in said stator and having a bore, a hollow shaft extending in a portion of said rotor bore, a hollow spindle extending partly in said rotor bore and partly in said hollow shaft, cooperating teeth in said rotor bore and spindle and in said hollow shaft and spindle said teeth providing a spiral engagement between said rotor and shaft, a spring in said hollow shaft and spindle tending to move them away from each other, a stem movable endwise in said rotor and abutting on said spindle, and means for shifting longitudinally said stem and spindle against the action of said spring.

10. An ignition magneto for combustion engines comprising a stator,a rotor rotatable in said stator and having a bore comprising a plain portion, inward teeth on another portion of said rotor bore, a hollow shaft loose in said plain portion of said rotor bore, inward teeth extending from the surface of said shaft bore, an endwise movable spindle having teeth engaging said inward hollow shaft teeth and teeth engaging said inward rotor bore teeth, said teeth of said spindle and said inward teeth of said rotor bore and hollow shaft providing a helicoidal engagement between said shaft and rotor, and means for shifting longitudinally said spindle.

In testimony whereof I have signed my name to this specification.

BRUNO ANTONIO QUINTAVALLE. 

